Here's an easy and yummy way to make a store bought brownie mix just a bit better.
Take your brownie mix and use applesauce instead of the oil. If your brownie mix doesn't call for oil, add about 1/4 to 1/2 cup; it will add moistness. After stirring everything together, add some crushed up Trader Joe's Candy Cane Joe Joe's. I added about 1 cup of the crushed cookies to a bowlful of brownies that would fill a 9 X 13 pan. Bake according to the directions on the box, but make sure you don't overbake.
After the brownies have cooled, frost the brownies. This recipe is delicious:
3 cups powdered sugar
2/3 cup unsweetened baking cocoa
1/3 cup milk
1/2 cup butter (melted)
1 tsp vanilla
Blend the sugar and the cocoa together in a bowl. Add the melted butter, milk, and vanilla to the sugar/cocoa blend. Beat for a few minutes until well blended. If you want richer and darker frosting, add about 1 T of coffee (or 1 tsp instant coffee) and more cocoa. For thicker frosting, adjust the amount of powdered sugar. This frosting is delicious for just about anything, and will be enough to frost an entire cake.
I've been tinkering with muffin mixes, too, and even the dollar muffin mixes can be made quite yummy with the addition of applesauce or mashed banana, vanilla, and chocolate chips or nuts. You might as well try it out, because you aren't out that much money if they don't work.